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Discussion Starter #1
I stripped the rear end housing in my car, wire-brushed looserust, and washed clean. I applied two coats of Master Series silver primer. That stuff is awesome. Dries hard as nails.

last night I brushed one coat of POR 15 chassis black over the Master Series primer. Thsi stuff is still soft after 24 hours. I can scrape it off with a fingernail. The leftover paint in the can I used is still as wet and thin as last night.

I stirred the can well with a paint stick to mix the solids off the bottom. I dispensed from the original container into a clean metal can.

Any ideas?
 

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Is the humidity high?

I thought the point of por15 was to put it on bare metal, ideally some that had been etched with their metal prep stuff.

I have put two coats on two separate rear ends and gotten pretty good results.
 

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Ummmm, whats the weather like there? I think that stuff cures better in high humidity, so if its really dry there, it may take it longer. Being in Washington, Id imagine its plenty humid there though.
 

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If I'm not mistaken, paint, even por15, dries because the solvent evaporates out of it. I think low humidity will promote faster drying.
 

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According to the POR instructions the stuff likes high humidity. Go Figure. I painted the bottom of my car in FL over July 4th weekend and by the time I finished the first coat it was dry enough for a second coat. I am pleased with the results so far (two years later).
 

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Thats right about most paints, Dan, but POR15 is a moisture-cured coating. If you take a can of it and squirt a drop of water into it, then replace the top, itll be hardened when you reopen it. It cures much faster in humid weather than in dry. Its basically the opposite of regular paint. :)
 

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Discussion Starter #7
Thanks for all the replies, guys.

I researched these paints quite a bit before purchasing. I corresponded some with Novatorious Rex who used lots of POR 15 during his recent restore. He wasn't 100% satisfied with the POR 15 primer, and suggested I try Master Series. Other folks on this site (do a search) praised the Master Series line of paints. It's worth noting that POR 15 recently introduced a silver primer similar to the Master Series.

I chose the Master Series primer and, as indicated above, am very pleased with the results. I chose the POR 15 topcoat because it is UV resistant. In order to get UV resistance in Master Series, you have to step up to their two-part paint. I didn't want to get into mixing before applying. Novatorious had great things to say about POR 15's topcoat so I decided to give it a try.

Both POR 15 and Master Series paints are moisture curing, meaning they'll cure faster in a high humidity environment. The two are very similar so I see no reason to think they'd be incompatible with one another.

It's been over 24 hours since I applied the POR 15. I can easily scrape it down to the Master Series primer with my fingernail. The two or so tablespoons of paint left in the bottom of the tin can is still thin liquid. In comparison, the leftover Master Series would dry rock hard overnight. It is not real humid here, but it is more humid today compared to earlier in the week when I applied the Master Series.

I'm going to drop by the paint store tomorrow and inquire with them. I'm not too pleased with the idea of stripping the rear end housing and starting over.
 

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Ron Slabaugh said:
It's been over 24 hours since I applied the POR 15. I can easily scrape it down to the Master Series primer with my fingernail. The two or so tablespoons of paint left in the bottom of the tin can is still thin liquid. In comparison, the leftover Master Series would dry rock hard overnight. It is not real humid here, but it is more humid today compared to earlier in the week when I applied the Master Series.

I'm going to drop by the paint store tomorrow and inquire with them. I'm not too pleased with the idea of stripping the rear end housing and starting over.
I had similar results when I used their "Blackcoat" stuff recently to paint my water pump. It took it almost a week for what was leftover in the jar to dry completely and a few days for the stuff I put on the pump itself to completely cure.

I used it again just because I had it leftover and I wasn't worried about corrosion on a cast aluminum part. :rolleyes:

It didn't take this long for the stuff to cure the last time I used it, but it was a different can. :confused:
 

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i am using the same topcoat for under my dash cause i had some left over....same kinda thing, but if i leave the top off even overnight it will harden up an 1/8 inch or so layer on top....

just some info....paints dry two ways, by a solvent evaporating (more of a mechanical bond) or a chemical bond when using a hardener (like most automotive paint) the solvent with a 2 part paint is used to make it sprayable, not for the drying of the paint....for a one part paint (house paint for example) the solvent keeps it liquid, when it evaporates it makes sie bond....
 

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how old is the paint

Hi, how old is the por-15 your using?, did you refrigerate it after using the first time?(seriously, look at the directions), I've used por-15 twice, both time's with good results, the first time i don't think i stirred it good enough and i can't remember if i got semi gloss or gloss black, but it's glossy in some places and semi in some places, the two times i've used the por15 i got the super starter kits, folllowed the directions to a T pretty much and my results are awesome, maybe your por-15 isn't drying or curing right because of the primer you put down first, i plan on eventually having my whole subframe and control armes done in semi gloss por 15, then a layer of the chassis coat black, the chassis coat is a top coat to be used over the por 15, since por 15 is so hard and strong and permanent by itself and you put down like two to 3 coats when u use it , i don't see a need for a primer, i just use the marine clean, then the metal prep, then put down like two light coats,
 

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OK guys, my apologies, I stand corrected.

What's that Paul always says about the "expert" advice readily available on the Internet?
 

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Discussion Starter #12
The one thing I dislike about this hobby is how you can spend countless hours of research and do everything according to directions and still have to end up doing it over again. So here's what I found out today:

The two day old left over paint in the tin can is still thin liquid. The POR 15 salesman and local Rep say this is normal. The Master Series Rep says it is not. He feels the leftover paint in the can should harden overnight.

So basically, POR 15 is pointing at Mater Series and Master Series is pointing at POR 15. The only agreement is that the paints are incompatible.

Tonight I wire-brushed three spots, removing the Chassis Coat plus a thin layer of Master Series. I wire-brushed the fourth spot to bare metal and coated it with Chassis Coat. I painted the other three areas with a lacquer spray paint, enamel spray paint and Chassis Coat. It will be interesting to review results tomorrow.
 

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Discussion Starter #13
The Chassis Coat adhered to bare metal very well. Even brush-applied, it laid down as smooth as if it were sprayed.

Chassis Coat applied to the wire-brushed Master Series surface adhered almost as well as to bare metal. I think it would be fine if I applied a second coat and let it cure completely.

The enamel spray paint adhered very well to the wire-brushed Master Series. I have to work really hard to chip it. It's pretty easy to scratch the surface, which is probably due to the relatively poor quality of rattle can paint.

The laquer-based rattle can adhesion is fair, but not as good as the others.

Por-15's website instructions for Chassis Coat differ considerably from those on the can. For example, when painting over a cured Por-15 surface, they recommend sanding with 300 grit paper followed by an application of Por 15 self etching primer, followed by Chassis Coat. I'm guessing that the Master Series surface is similar to a cured Por-15 surface, requiring this level of surface prep. The wire brush on my die grinder was similar to this prep, allowing the Por-15 to perform reasonably well.

Master Series claims any paint can be applied directly over their silver rust preventative paint for up to seven days. After seven days they recommend sanding the surface with 240 grit paper prior to topcoating.

I spoke with the Master Series rep yesterday. His opinion was that any moisture-cured paint that would not set up in the can overnight was not worth applying. When topcoating Master Series rust preventative paint, he recommended Master Series two-part urethane for best results. No special prep to the rust preventative paint is necessary.

Alternatively, he said I could strip the Chassis Black and apply a fresh thin coat of rust preventative paint. Once it gets tacky, apply a thin coat of my favorite rattle can paint. Once that gets tacky, apply a second coat of rattle can paint. He said that when the Master Series cured, it would pull some of the rattle can paint into it and create a reasonably durable surface (although not as good as their two-part urethane.)

A lot of people have used Por-15 with good results so there is no denying it is good paint. I think to achieve consistently good results, you need to use all of their products (marine clean, metal ready, etc.) and follow their instructions specifically. I personally don't like the fact that you must prepare their prime coat with sandpaper and self etching primer prior to applying their Chassis Coat topcoat.

The bottom line is this: Do not mix Master Series and Por 15.
 

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The POR15 salesman and local rep speaketh with forked tongue! I can assure that that is NOT normal, Ron. I know its a good product, but it would seem that what happened is you got a can that would be considered a "bad batch". That happens occasionally with paint. But instead of trying to pull the wool over your eyes, the LEAST they should have done was offer to replace it for you. It may or may not be compatible with Master Series (I suspect that it is), but Master Series has nothing to do with the leftover paint in your can that isnt curing! Ask them to explain THAT! I would make them replace it, Ron. Just my 1½ cents worth. :)
 

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Discussion Starter #15
I found a set of instructions on a Por15 supplier website. It suggested applying the topcoat while the rust preventative paint is still tacky.

So I found a piece of sand blasted angle iron in my garage. I applied one coat of Master Series silver. After one hour (it was still sticky) I painted half of it with Chassis Coat and half with my cheapo rattle can enamel.

I applied a second coat to both about 8-hours later. I applied a third coat of rattle can about an hour later.

Over 24 hours have passed and adhesion of both paints is amazing. I can not scratch the surface of either with my fingernail. However, I shot each with my single pump BB gun from about 20-feet away. Both chipped where the BB hit.

Thus, it does not appear at this point that the Chassis Coat is any more durable than the rattle can. I'll give it another few days cure time and retest just for grins.

The Chassis Coat does have a higher solids content than the rattle can paint. It fills in the lows and provides a nice flat surface. I think about five coats of rattle can would be necessary to get the same flatness. The satin finish of the Chassis Coat is a bit more desirable for frame paint as well (as compared to the high gloss rattle can).

So in order to make the Chassis Coat adhere (and probably Blackcoat as well), it needs to be applied while the prime coat is still tacky. Alternatively, you can wait until the prime coat is hard and sand it with 240 grit paper followed by an application of self etching primer. It is almost certain satisfactory results will not be obtained applying over a hard cured primer or paint.
 

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I have used POR 15 several times with very good results over both bare and previously painted surfaces. I think two thin coats over bare metal would provide the best surface, there is something about the buildup of paint that allows it to chip. I've always used the glossy without top coat.
 

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I'VE USED IT TWICE AND IT LOOKS OUTSTANDING ON MT 10 BOLT AND SURROUNDING COMPONENTS. :yes:


BUMP FOR THOSE THAT NEED THE INTEL
 

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I'VE USED IT TWICE AND IT LOOKS OUTSTANDING ON MT 10 BOLT AND SURROUNDING COMPONENTS. :yes:


BUMP FOR THOSE THAT NEED THE INTEL
I've probably used a few gallons of it by now, and in my experience the biggest and most important part of application is that the metal underneath is as clean chemically and has as much "tooth" as you can give it. On smooth surfaces it can chip and come up in sheets. On rougher or sandblasted surfaces it can end up being practically bomb-proof it you lay it on right.
 
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